Audra Smanski began harboring fears for his young son’s safety and locks the doors to her home, thinking it is the little she can do to feel safe.

And Raj Bala is overcome with sadness each time he enters his workplace at MIT’s Stata Center, near the spot prosecutors say one of the Tsarnaev brothers killed a campus police officer, Sean Collier, as he sat in his cruiser.

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Across Cambridge, a city of Ivy League sensibilities, progressive politics, and much-heralded diversity, the Marathon bombings’ aftermath has brought aftershocks as residents confront the fact that two of their own may have committed such horror.

“It’s just a terrible feeling of emptiness and hurt,’’ said Gail Seidman, whose family has owned University Stationery Co. on Massachusetts Avenue since 1944. “We are all just doing the best we can. But we will never be the same.”

The bombings have felt like a personal afront in this city, which prides itself on its openness and welcoming attitude. The suspects, brothers Dzhokhar and Tamerlan Tsarnaev, attended Cambridge’s only high school and sometimes went to Friday prayers at the mosque near their Norfolk Street home. Cambridge was where they allegedly killed Collier on the MIT campus, before leading police in a wild gunfight that left Tamerlan dead and Dzhokhar in federal custody.

“We had been hit, metaphorically, by an antipersonnel bomb that exploded and ripped out our trust and faith in who we are and what we do. It exposed our doubts,’’ said Aaronson, a longtime Cambridge Rindge and Latin teacher who knew Dzhokhar and who lives three doors down from where the brothers lived on Norfolk Street.

The Dzhokhar he knew was a wrestler with a heart of gold. They had talked about Chechnya and Dzhokhar’s gratitude that he had found sanctuary, friendship, and a beloved school in Cambridge.

“This is what we are so proud of in this city — that we give him sanctuary. How dare he?’’ said Aaronson. “I knew this child, and I thought I knew him well. But then he wreaked such havoc and such destruction on the most beautiful event.”

It was too much for Aaronson, who also knew victims of the attacks. He said he suffered a nervous breakdown.

To be sure, Cambridge is not immune to tragedy. Just last year, the city recoiled in horror after 16-year-old Charlene Holmes was killed in June 2012 in an apparent drive-by shooting on Willow Street. And many residents still recall the 1997 slaying of 10-year-old Jeffrey Curley of Cambridge. The two men convicted of killing him are serving life sentences.

But this is different, residents here say.

“This is a game changer,’’ said City Councilor Craig Kelley. “This is a world view-shifting event, and I think we are all struggling in a place that is inclusive, that is loving and supportive, and everything that Cambridge is. We are all struggling to figure out what the heck all this means to us and our civic identity.”

Nancy Rappaport, a Cambridge child psychiatrist who works with school and traumatized children, said Cambridge is experiencing a form of guilt by association because both suspects and victims live in the same city.

“Whenever a community is close to an alleged criminal, it is understandable that there are feelings of guilt, shame, and anger,’’ said Rappaport, speaking generally. “The tyranny of hindsight can occur where the community asks, ‘How could we have not known?’ Even when a community has all the resources, sometimes bad things happen.”

City, school, and faith officials have been holding vigils, school assemblies, and prayer services.

“In my community people are going to [Cambridge Rindge and Latin] to show their solidarity,’’ said the Rev. Holly Lyman Antolini of St. James’s Episcopal Church in North Cambridge. “We walked to the mosque from city hall to express our trust in each other and state out loud that ‘I am not afraid.’ ”

Still, many here say, the road forward will be long and difficult. As a spring sun glistened on Cambridge Rindge and Latin School, Mary Thornton said she is still troubled.

“It can happen any place, but when it happens in your backyard it is frightening,’’ said Thornton, a resident of 40 years. “When you think of all the victims who died or who lost their limbs, you just can’t wrap your head around it.”

Smanski, hoping to cope, prays at Christ the King Presbyterian Church on Prospect Street. She avoids news photographs of the bombings.

“I’ve been a little more fearful for my child,’’ Smanski said of her 11-month Jonathon. “I’ve been more anxious about how to keep him safe.”

Bala said he has been speaking to many MIT police officers, hoping to learn more about Collier to deepen his own understanding of the slain officer.

And Aaronson said he has been able to free himself from depression after seeking therapy and being embraced by friends in the Cambridge community.

In Inman Square, Riva Poor, a 76-year-old author and lecturer, said she has compartmentalized her misery, keeping it in a corner.

“It’s a horrible thing,’’ she said of the bombings and their aftermath. “I don’t want to think about it. I can’t do anything about it because it is nothing I can fix. And I’m fixer.”

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